Detection of impurities



Patented May 17, 1949 cmrso PATENT OFFICE Abpi'icafioii I2, 1944, Serial No. 544,562

1 ihweiitio h' to the eeteetien er ii'nfaii'r itie's the atmtsehere or other gases their elimination therefrom. V

eem'unetion "with air (membrane or buildings and other spacesemblem w r arises is the elimination I of toxic 'oth'er aaneertw or iinfiui'ities from the atmosthere.

Ear-1y attem ts to eliminate materials concerned themselves with sa nymg fresh air, as by opening windows, ventilators erthe l il ie, or by pbtltited air, under manual 'etntrei area at the judgment or an operator.

This, in turn, led to attemiits emsiri' deterirhne the er replateiiie there which would removed-tempo es et -ah average qbrbifitirtivn to their 1':irod'tu'z'tio'n.

such systems nave ben toeaduhsatisfa' cry for a hum-beret reasons. ii i aiidell eoatrei, of cohfise, was dependent entire-1y "the 'iud'gment of the operator.

Any new or iess *torrt" precess does-hot adapt itself sudden treine Variations, and obtain satis'taetdry Ventilation only when set to restate the mai-fhhuiham'oiiet titan nee'es sary under the most extreme conditions.

This leads to inefficiency, particularly loss of heat and tower, as will reaiiny be appreciated from the consideration or a "building as a foundry, where 'at times there may be excessive amounts of dust, sfi'io'kefiiid other aerete'rieus substances in the air, if a ventilator, 'fdrihstance bfie 'diiifiped with a ran, be adjusted to remove "these impuritiestfidf the worst eonditio'ns, ig'reat 'qfiaihtities' 6f heated air are extracted at times when there is 'fio hecs's'ity for such extraction, and, particularly in winter weather, useful neat i's'fli'iis lost.

If an accurate control be ovided which win operate 'viiti'lai'tiff and the like in aceeraance with the quantities of impurities carried by the air, it'w'ill be'afii'areiit that great savings can b'e effected.

However, the'impurities which normally-are present are of a very'finelydivided character,- frequently minute particles of dust, carbon and the like, so that an accurate detertirination of the ouantity of them by purely rr-ieehanical means is impracticable, while variations in fighting, both due to day-tight and artificial sources, have rendered the electrenic determination here'to fore unsatisfactory.

--It an obi eot of the present invention tomvercome the difiiculties heretofore experienced in '3 Claims. (Cl. 981) controlling ventilating and conditioning apparatus in accordance with the quantities of nhpurities present within a struttu re.

Another object is to provide means for determinin accurately "the quantities at "such impurities, determination will not be ihfluenced by extraneous iactorssuch as variationsin light; barometric pressure, temperature, and the like.

-It'is a further obie'ct-ol? the invention to prm vide animproved nreans for' measuring impurities in the air which may'he'iised teacttiate ventilating or similar apparatus, soth'at -air which has Q been contaminated many preaetermmed extent may be replaced.

Another object is to provide an improved method of measuring thequantity of impurities in a gaseous medium.

Other 'olofrects win hereinafter appear.

The invention will he better understood from the description of one' practical apparatus which constitutes one embodiment thereof, illustrated in the accompanying drawings, in which:

Figure 1 is a perspective of the assembled apparatus, the front er cover being broken away; and,

Figure -2 a diagrammatic illustration or the circuits and :parts associated therewith.

The apparatus illustrated is shown as asseihbld in a compact unit enclosed in a gen erally rectangular casing'having a bottom Ltop Lends 3 and 4, aback -5 and 'anfront or cover plate't, secured to the peripheral flanges I of the top, bottom and ends as byyscrews 8.

Rings 9 are fixed to the top 2 by which the entire device may be suspended in any desired loca tion, it being unnecessary that itbe rigidly connected with any other "apparatus.

Extending horizontally within the casing is Pa rectangular 'con'duit 'HJ defining a light-tight passagefor air and gases, this conduit being in communication with a downwardly extending 'inlet {I which, in turn, communicates with a larger intake space defined by a horizontal shelf f2 and vertical end T3,- which, with end '4, back 5 and front 6 rormsa compartment open at its b'ottoin except for transversel extending bar [4 which is fixed to the bottom fi'an'ges [1, it being understood that the bottom I extends merely from the end 3 to vertical wall [3.

Above the top of conduit 10, adjacent its end remote rrom intake passage H, extends a short rectangular 301 16111 11; 1-5 119311112 OIO'SB'd r'ldsy'and, adjacent its right hand end (as seen-in l' igure *1) a deplidihfi 'fii tri dh 15 communicating with the interior of conduit l and at its other end an upwardly extending portion H which is connected at an opening in the top 2, to serve as an outlet for air and gases which have passed through conduit Ill.

The passages within the inlet and outlet conduits consist of mutually offset parts, causing the air to follow a sinuous path and preventing any rays of light from the outside from entering conduit Ill.

The ends of conduit ID are closed by plugs l8 and I9 which extend through the ends 3 and 4 of the casing and are removable from the exterior thereof, one of which US) carries a source of light 20, which is illustrated as an electric light bulb, and the other of which (l8) carries a photo-electric cell 2|, these being connected by cables or electrical conduits 22, 23 and 24 to the electrical apparatus which is positioned upon and adjacent to two panels 25 and 26.

Supported upon the bar I4 is a socket 21 which carries an ordinary electric incandescent lamp 28, positioned immediately below the opening at the lower end of the depending conduit The circuits and the manner of operation of the device will be more apparent from the description of Figure 2 of the drawing.

In this figure, an electric motor is shown at 29, this being connected to a blower or other airhandling device 30 which it is desired to operate in some relation to the amount of smoke, dust particles or the like contained in the air.

Current is supplied from any suitable source, such as a central power station, through electrical conductors 3|a. and 3|b to the primary 32 of a transformer, which, in turn, furnishes the current required by the parts of the apparatus contained in the casing.

From conductors 3|a and b branch conductors 32a and b respectively, lead to a relay 33 through which current may be supplied to operate the motor 29.

The electro-magnetic coil for operating the relay is shown at 34 and is supplied with current from conductors 32a and b through conductors 35 connected from wire 32a directly to one end of the coil and through a conductor 36 which extends to one contact 31 of a relay, the other contact 38 of which is connected by a conductor 39 to the conductor 321), the contacts 31 and 38 being controlled by the apparatus which is actuated by current induced in secondary 40 of the constant voltage transformer which includes primary 32. This secondary is connected by conductors Ma and 4|b to the primaries 42 and 43 of two more transformers.

The secondary 44 of the first of these, associated with primary 42, is connected by conductors 45a and 45b and conductor 22a, through a rheostat 45, to supply current to electric light bulb 20. It will be understood that parts of both conductors 22a and 45b are included in conduit 22 of the first figure.

In the transformer including primary 43 are three secondary coils 41, 48 and 49.

From secondary 41 conductors 50a and 50b extend to the filaments of two thermo-ionic valves or tubes and 52, conductor 50b being grounded as indicated at 53.

From secondary 48 conductors 54a and 17 extend, the former being connected to a condenser 55 and the latter to one end of the filament of a rectifier tube 56.

The two plates of rectifier tube 56 are connected 1 by conductors 51a and b to the ends of secondary 49.

From secondary 49 a central tap 58 connects to a conductor 59, one end of which is branched, one branch being connected to condenser 55 and the other branch to condenser 60. Conductor 59 extends upwardly as seen in Figure 2, to a resistance 6|, whichis connected by conductors 62 and 24 to one element of the photocell 2| and also to the grid of thermionic valve 5|.

From the plate of thermionic valve 5| to the grid of the thermionic valve 52 extends a conductor 53 to which are connected two resistances B4 and 65.

The other end of resistance 64 is connected by conductor 66 to conductor 59, while the other end of resistance 35 is conducted by a conductor 61 to a conductor 68 which extends from condenser 60 to the coil 69 of the relay including contacts 3! and 38.

From the other end of this relay coil 69, a conductor it! extends to the plact of thermionic valve 52.

In parallel with the coil 69, between conductors 68 and 70, is a condenser The lower end of conductor 69 is branched, one branch, as above indicated, being connected to condenser 90, and the other being connected to the coil of a filter choke coil 12. The other end of this coil is connected to the filament of rectifier tube 56.

Extending between conductors 59 and 68 is a conductor including three fixed resistances I3, 14 and I5 and two variable resistances, such as potentiometers l5 and H.

From the movable contact of potentiometer I6 and conductor 18 extends to the other element the photo-electric cell 2|, having a branch connected to the cathode of thermionic valve 5|.

From the variable contact or potentiometer TI and conductor 79 extends the cathode of thermionic valve 52.

In one example which has been actually installed and found to operate satisfactorily on volts, 60 cycle, line current at lines 3|a and 3|b, the following have been found satisfactory constants.

Rheostat 46 15 ohms Light bulb 20 6 volts,

21 candle power Rectifier tube 5U4G Thermionic valves 5| and 52. 6-J5 Resistance 0| 60 megohms Resistance 64 3 megohms Resistance 65 3500 megohms Resistance 73 1000 megohms Resistance l4 7000 megohms Resistance 15 1000 megohms Potentiometer 16 1000 megohms Potentiometer H 2000 megohms Condenser 2 microfarads Condensers 55 and 60 4 microfarads Relay coil 59 6000 ohms The circuit of bulb 28 is not shown, as this is connected in conventional manner to the line current.

The function of this bulb is to induce a current of air or draft through conduits H, II] and I5 to insure conduit l0 being filled at all times with a representatives sample of the atmosphere in which the apparatus is positioned, and it is found that a relatively small light bulb of conventional type induces suflicient connection for this purpose.

Light from this bulb is prevented from entering casing ill by the offset arrangement of its intake ll, while light from the interior of the building in which the device may be positioned is further prevented from entering conduit I!) by the ofiset arrangement of the outlet l5, so that the light beam emitted by the bulb 20 supplies the only illumination within the casing I0, and, as this light may be regulated by adjustment of rheostat 46, the quantity which reaches the photo-cell 2| may be made accurately proportionate to the amount of smoke and/or dust particles and other suspended solids in the atmosphere within the casing 10.

Also, by this arrangement the length of the column of mixed air, smoke, dust and the like may be determined to permit the measurement of these suspended solids with any desired degree of accuracy, as it will be apparent that the amount of light obstructed by the solids is proportional to the length of the column through which the light beam must travel, and hence, to the length of casing l0.

Also, due to the projecting ends of the casing Ill, both the bulb 20 and cell 2! are positioned out of the direct course of the air currents moving through casing l between inlet H and outlet l6, and are thus protected from becoming obscured by deposits of dust or smoke particles.

While the tortuous passage of air through inlet H, casing l0 and outlet I6 is sufiicient to exclude external light, the bends are large and open, and, in view of the relatively slow flow of the air through them, do not materially obstruct its passage so that small amount of heat supplied by lamp 28 is found quite adequate in most situations, although, of course, any means for causing the air flow might well be employed, such as a small fan, blower or the like in situations where a higher speed of passage may be desired.

The apparatus permits the continuous sampling of the atmosphere together with prompt, automatic control of any apparatus to eliminate any undesirable conditions as these arise.

While I have described the illustrated embodiment of my invention in some particularity, obviously many others will readily occur to those skilled in this art, and I do not, therefore, limit myself to the precise details shown and described herein, but claim as my invention all embodiments, variations and modifications coming within the scope of the appended claims.

I claim:

1. Measuring apparatus comprising a casing, a horizontal extending conduit therein for sampling air to be conditioned in an enclosure, removable light-tight closures at the ends of said conduit,

a source of light within said conduit adjacent one of said closures, a light sensitive element within said conduit and an air sample therein and adjacent the other said closures, a depending inlet conduit communicating with said first mentioned conduit, an upwardly extending exhaust conduit communicating with said first mentioned conduit adjacent its other end and having a plurality of off-sets, the inlet and outlet conduits communicating with the first mentioned conduit between the source of light and the light sensitive element, a heating device positioned below the lower end of the inlet conduit, elec trical amplifying apparatus within the casing and responsive to said light sensitive element and arranged to operate a relay, a source of current controlled by the relay, and electrically operated air conditioning apparatus for said enclosure operated by said current and controlled by the relay.

2. Measuring apparatus comprising a casing, a horizontal extending conduit therein for sampling air to be conditioned in an enclosure, removable light-tight closures at the ends of said conduit, said closures being accessible from the exterior of the housing, a source of light within said conduit adjacent one of said closures, a light sensitive element within said conduit and an air sample therein and adjacent the other said closures, a depending inlet conduit communicating with said first mentioned conduit, an upwardly extending exhaust conduit communicating with said first mentioned conduit adjacent its other end and having a plurality of offsets, the inlet and outlet conduits communicating with the first mentioned conduit between the source of light and the light sensitive element, a heating device positioned below the lower end of the inlet conduit, electrical amplifying apparatus within the casing and responsive to said light sensitive element and arranged to operate a relay, a source of current controlled by the relay, and electrically operated air conditioning apparatus for said enclosure operated by said current and controlled by the relay.

3. Measuring apparatus comprising a horizontally extending conduit for sampling air to be conditioned in an enclosure, vertically extending inlet and outlet conduits connected therewith on separate sides thereof, said outlet conduit having a plurality of changes in direction and said inlet conduit extending downwardly from said horizontal conduit and below said outlet conduit, a source of light positioned within the first mentioned conduit between one end thereof and one of said vertically extending conduits, a light sensitive element positioned within the first mentioned conduit between the other end thereof and the other vertically extending conduit, and light excluding closures at the ends of the first mentioned conduit, and draft inducing means arranged adjacent one of said vertically extending conduits comprising a, heating element, and air conditioning apparatus for said enclosure controlled by said light sensitive element.

REX D. McDILL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 878,456 Darwin Feb. 4, 1908 892,241 Freise June 30, 1908 1,626,663 Brace May 3, 1927 1,743,175 Wensley et al. Jan. 14, 1930 1,878,010 Spahr Sept. 20, 1932 1,937,722 Simon et al. Dec. 5, 1933 2,046,714 Wilson et a1 July 7, 1936 2,056,663 Foulke Oct. 6, 1936 2,185,361 Towne Jan. 2, 1940 2,311,374 Farmer et al. Feb. 16, 1943 2,339,987 Evans Jan. 25, 1944 

